Exercise is the key to maintaining Vitamin D levels in winter, study finds

Medical Xpress / University of Bath / Advanced Science ^ | May 14, 2025 | Oliver J. Perkin et al

[ConservativeMind]

New research has revealed that regular, moderate-intensity exercise helps maintain crucial vitamin D levels during the darker months—even without weight loss or supplements.

Researchers found that people with overweight and obesity who completed a 10‑week indoor exercise program over winter experienced significantly smaller drops in vitamin D levels compared to those who didn't exercise—even though their body weight was deliberately maintained.

The program involved four sessions per week: two treadmill walks, one longer steady‑state bike ride, and one high‑intensity interval bike session.

Notably, exercise completely preserved the body's active form of vitamin D (1,25(OH)₂D₃), which plays a key role in supporting bone health, the immune system, and various organs. Previous studies suggest that vitamin D supplements alone do not help maintain this active form.

Lead author Dr. Oly Perkin, from the Centre for Nutrition, Exercise and Metabolism, Department for Health at the University of Bath, said, "This is the first study to show that exercise alone can protect against the winter dip in vitamin D. It's a powerful reminder that we still have lots to learn about how exercise benefits our health."

Key findings:

—People who exercised saw a smaller drop in their overall vitamin D levels over winter—about 15%, compared to a 25% drop in those who didn't exercise.

—Importantly, those who exercised kept healthy levels of the active form of vitamin D, which helps support the immune system and bone health. In the non‑exercising group, levels of this active form fell by 15%.

—Weight was kept stable throughout the study, proving the effect was due to exercise—not weight loss.

[ConservativeMind]

Exercise helps your body maintain a good vitamin D status—even without any vitamin D supplements.

This is not an intuitive finding.

[ConservativeMind]

The “Take Charge Of Your Health” Ping List
This high volume ping list is for health articles and studies which describe something you or your doctor, when informed, may be able to immediately implement for your benefit.

Email me to get on either the “Common/Top Issues” (20 - 25% fewer pings) or “Everything” list.

[mass55th]

I have an overactive para-thyroid that produces more Vitamin D than I need, so I can sit on my ass and do nothing.

[ransomnote]

Thank you for posting this info.

I now have doubts about the standard ‘healthy levels’ of Vitamin D. According to those offering advice on steering clear of Covid or recoverying from it, the FDA recommends about 1/10 of the amount of D we’d actually benefit from.

I think the last FDA article I read talked about getting 600 - 800 IU per day to maintain healthy levels, but after reading non-governmental sources, I should take almost 10 times that amount.

[roving]

I just take a pill.

[ConservativeMind]

I average around 2,800 - 3,000 IUs a day.

[ConservativeMind]

Please double-check your understanding, because your para-thyroid can’t make vitamin D.

[mass55th]

"Please double-check your understanding, because your para-thyroid can’t make vitamin D."

I was on Vitamin D for quite a while, but they took me off of it because my numbers were too high. Vitamin D helps your body absorb calcium, but since my calcium levels are already higher than normal, I can't take it. Normal range for Calcium is 8.7 - 10.3 mg/dL. Mine always runs about 10.5 mg/dL.

[Cobra64]

My wife and I have been taking 10,000 IU since Covid. Do not forget K2 and Mg.

[metmom]

No, but it’s an excellent thing to know.

I’ll have to break out the snow shoes more next year.

[Bobbyvotes]

Daily mild aerobic exercise is beyond fantastic benefits. I am a living example. At age 85 I require no prescriptions except minimum dose Lisinopril. If I eliminate sodium I could drop Lisinopril. But I can’t eat salt free stuff. Before daily exercise 30 years ago, I had bad heart function, was borderline diabetic and high blood pressure. Now heart is without issues, I can eat sugar, and no pain in any joints or muscles. Daily exercise beats all medical treatments in my case.

[Bobbyvotes]

Living in Florida and mowing my lawn, I do not take any D vitamin or any other supplements. Take Only one multi vitamin pill daily which has some D vitamin. My doctor sends me for blood work every 4 months. That shows D vitamin levels are normal.

[newfreep]

four sessions per week: two treadmill walks, one longer steady‑state bike ride, and one high‑intensity interval bike session.

3 days of 30-40 minutes of HIIT on an elliptical - most efficient/effective aerobic workout
3 days of free weight/machines

As a "seasoned citizen", the last time I saw a doctor was in my early 40s when I injured my shoulder.

The last flu I had was 15+ years ago...or longer...and thankfully never took the clot-shot.

Daily vitamins & supplements include:
Multi for 55+ (whole food based)
C 1000mg
D3+K2 5000 IU
Quercetin
Omega 3-6-9
Zinc

But exercise is most important to ensure the diet/vit/supp work their best.

[newfreep]

It’s also VERY important to get a quality heart rate monitor!

An absolute must for HIIT workouts and any workout to maintain a safe heart beat rate.

I’m using this US designed w/rechargeable battery - FITCENT Rechargeable Heart Rate Monitor Chest Strap + the free “Polar” phone app to display my heart beat in real time and stay in HIIT zone.
https://www.amazon.com/dp/B0995HMQ17

[Freee-dame]

“ Daily mild aerobic exercise is beyond fantastic benefits.”

This is so true. One of the many reasons I love living in Florida is that I can go outside and walk or swim every day.

[BrandtMichaels]

I decided to simply add mushrooms to my diet.

They have zinc, vitamin C & D and most every mineral
needed for immunity. If you dry them out in the sun,
they absorb even more vitamin D.